Magnetic holder for electrophoresis material



MAGNETIC HOLDER FOR ELECTROPHORESIS MATERIAL Filed March 15, 1965 J. M.BELOTE ET AL Aug. 6, 1968 2 Sheets-Sheet l FIG 2 INVENTORS JAMES M.BELOTE DONALD CHURCHILL HERBERT J. EARLE CHARLES GELMAN 4 W W 1 mATTORNEYS 1968 I M. BELOTE ET A1. 3,396,096

MAGNETIC HOLDER FOR ELECTROPHORESIS MATERIAL Filed March 15, 1965 2Sheets-Sheet 2 INVENTORS DONALD HERBERT J. EARLE HARLES GELMAN W M W M AT TOR/VEVS United States Patent 3,396,096 MAGNETIQ HOLDER FORELECTROPHORESIS MATERIAL James M. Relate, Donald Churchill, Herbert J.Earle, and

Charles Gelrnan, Ann Arbor, Mich, assignors to Gelman InstrumentCompany, Ann Arbor, Mich., a corporation of Michigan Filed Mar. 15,1965, Ser. No. 439,654 7 Claims. (Cl. 204-499) This invention relates toa magnetic holder for electrophoresis material and more particularly toan electrophoresis chamber and combined apparatus for holdingelectrophoresis material.

As a general background, it might be stated that electrophoresis is aname applied to a technique used in medical research and diagnosis whichinvolves analyzing the molecules of body fluids such as serum, proteins,hemoglobin and other protein substances that vary in molec ular weight.The process requires passing an electric current through a strip offilter material, gel, or porous plastic that has had a sample fluidapplied to it. The electric current forces the sample molecules to movealong the strip, with distances depending on the charge, molecularweight, and size, that is, a certain prescribed current will move alight molecule farther than a heavier one. The result on a strip offilter material is a pattern of well-defined bands which are thensometimes colored to facilitate the examination and analysis.

The electrophoresis process involves the use of filter material which isapt to be rather delicate and subject to fracture and breaking. Itusually consists of small strips of material about 1" in width and 6 inlength but in some cases the strips are 20" long and of a wider width.These strips are bridged over two ridges in an electrophoresis chamberand an electrical potential is applied to the paper generally by lettingthe ends submerge into two separate bodies of liquid which are subjectedto the proper electrical circuit or by using Wicks to connect the wettedfilter with the liquid body. It has been a problem to fasten the ends ofthese strips suitably in a manner to prevent the sagging of the stripwhich might cause a malfunction of the process and to prevent damage orinjury to the strip itself. This has been done in the past by resilientclamps and other clamping devices held by gravity or mechanical forcebut the problem has never been successfully solved.

It is an object of the present invention to include in theelectrophoresis chamber a magnetic holding arrangement which isextremely simple and inexpensive and yet one which permits firm clampingof the sample strips in a manner which tends to apply slight tension tothe strips to maintain suitable tension thereon as the strips bridge thesupports.

It is a further object of the invention to provide a magnetic holdingarrangement composed of elements which position in a manner to grip theelectrophoresis material in a positive way, the elements being soprovided with indicia that they may be properly applied relative to thepolarity of the magnetic holding devices, thus insuring a positivepositioning and the intended holding function.

Other objects and features of the invention relating to details ofconstruction and operation will be apparent in the following descriptionand claims.

Drawings accompany the disclosure and the various views thereof may bebriefly described as:

3,396,096 Patented Aug. 6, 1968 FIGURE 1, a perspective view of anelectrophoresis chamber with cover removed.

FIGURE 2, a plan view of an electrophoresis chamber.

FIGURE 3, a sectional view on line 3-3 of FIGURE 2 with a cover inposition.

FIGURE 4, a sectional view on line 4-4 of FIGURE 2 with cover inposition.

Referring to the drawings:

The electrophoresis chamber is preferably formed as a shallow tray 20which can be molded of a plastic glass or ceramic material, this trayhaving a center partition wall 22 extending between ends 24 and 26 aboutmidway between sides 28 and 30. Between the central partition 22 and therespective walls 28 and 30 are elongate support ridges 32 and 34 whichextend outwardly from the end wall 26 to a point just short of the endwall 24. These support ridges 32 and 34 are higher than the centralseptum wall 22. In general, the septum wall is about onehalf the heighthof the outer walls of the chamber and the support ridges are abouttwo-thirds the heighth of the outer walls. It the structure is moldedplastic, the center partition and the support ridges can be molded intothe structure so that they are hollow as shown in the sectional viewused in FIGURES 3 and 4. This provides an elongate chamber 36 and 38below the support ridges 32 and 34. Also molded into the bottom aresmall elongate depressions which provide supporting bosses 40 on thebottom of the tray.

The end wall 26 has two connecting posts 42 for the attachment ofelectrical connections and from the inside of these posts are electricalconductor elements 44 and 46 extending downwardly into the tray onopposite sides of the partition wall 22. A cover for the device ispreferably formed of a transparent sheet of plastic material 50 whichhas a fairly snug fit on the top of the tray 20. This cover has bosses52 for-med therein to rigidity the cover and to provide drip areas forliquid which may condense on the cover.

On the inside undersurface of the outside wall of the ridges 32 and 34,extending substantially the length of the tray, is positioned anelongate strip of magnetic material. This is preferably made ofpermanent magnetic material. However, it may be a metal alloy capable ofattracting a magnet.

One embodiment can be molded strip of rubber or thermoplastic containingmagnetic particles which creates a permanent magnet in the rubber. Thiscan be fastened in place by a suitable adhesive to the inside surface onthe ridge 32 or 34 or it can be molded into the plastic as the tray isformed. Other methods of fastening can be utilized. The strip ispreferably of narrower width than the overall height of the supportingridges 32-34 so that the strip can lie spaced downwardly from the top ofthe ridge. The strip material has a definite polarity characteristic andit is preferable that the two strips have a polarity in the samedirection. In FIGURE 3, the strip 60 is shown with a point 62 and a tailformation 64 to indicate this polarity.

To cooperate with these strips, there is provided a plurality of shortholding elements also formed with an arrow configuration as shown inFIGURE 1. These elements 70 are also of magnetic material. They can beof metal but are preferably formed of the magnetic rubber strippingpreviously described. These short elements also V have a polarity in thedirection of the arrow in which they are formed and they work best ifdisposed in the 3 proper relation to the underlying magnetic strippointing toward the electrodes of the electrophoresis chamber. Therubber material also has the advantage that it has a frictionalengagement with the electrophoresis strips 80 which are to be positionedin a bridging relation over the support ridges 3234.

When the electrophoresis material is disposed over these ridges, theholding elements 70 are gently pressed onto the material preferably fromthe top and they thus have a tendency to move down by reason of themagnetic forces, pulling the strip taut as they move. This tendency ofthe elements 70 to move down toward the magnetic field, opposite polesattracting each other, applies a slight tension on the specimen strips80 which is maintained by friction and the forces of attraction betweenthe strips and holding elements as the electrophoresis process proceeds.

Certain magnetic rubber stripping that is available commercially has athin layer of magnetic rubber material on one side of the strippingbacked by ordinary rubber material. There is a north pole at oneelongated edge of the magnetic layer and a south pole at the otherelongated edge of the layer, both poles being on the same side as thestripping. If the holding elements 70 and the strips 60 are made of suchmagnetic rubber stripping, each piece of the stripping is a permanentmagnet. In order to have a given element 70* and a strip 60 attract eachother and hold the electrophoresis material on a support edge, theholding element should be oriented such that its north pole is oppositethe strips south pole and its south pole is opposite the strips northpole. This is because opposite poles of two magnets attract each other.

The arrow configuration for the strips and holding elements helps anoperator to orient the holding elements properly without requiring himto identify their poles. Referring to FIGURE 3, the strip 60 shown therehas a point 62 at its right-hand end and a tail '64 at its lefthand end.Assume that there is a north pole all along the upper elongated edge 63of strip 60 and a south pole all along the lower elongated edge 64. Asviewed in FIGURE 3, these poles are at the back side of the strip whereit abuts the vertical wall of support ridge 34. Considering now one ofthe holding elements 70 shown in dashed lines, it has a point 72 and atail 74 at the same respective ends as the strip 60. However, the polesof element 70 are inverted relative to those of strip 60, the north polebeing along the lower edge and the south pole being along the upperedge. The magnetic layer of holding element 70 abuts the electrophoresismaterial 80 (FIGURE 4) and faces the magnetic layer of strip 60 on theother side of support ridge 34.

It is not essential to have both the strips 60 and holding elements 70act as permanent magnets. One or the other may be made of non-permanentmagnetic material such as iron or other suitable metal. In this case, itis not necessary to orient the holding elements as carefully, but it isdesirable, nevertheless, to use an elongated holding element and applyit to the support ridge parallel to and slightly above a given strip 60such that the element will slide down the support ridge to a positiondirectly opposite the strip as illustrated in FIGURE 4, therebytensioning the electrophoresis material as previously described.Consider the example where the strips are permanent magnets and theholding elements are made of nonpermanent magnetic material. Themagnetic field of the strips has lines of force (flux lines) which leavefrom its north pole, curve around and enter at its south pole. Theselines of force pass through the holding element and cause it to act as atemporary magnet such that it is attracted to the strip and holds theelectrophoresis material 80 in place. As has been indicated, the sameresult is achieved if the holding elements 70 are permanent magnets andthe strips 60 are made of non-permanent magnetic material.

It will be understood, of course, that in the process the chamber isfilled with a suitable electrolytic bath 82 of suflicient depth to reachthe ends of the strips as they are disposed over the supporting ridges32-34. The specimen strips are preferably formed of a microporouscellulose polyacetate that gives a uniform pore distribution andeliminates impurities which might impair the electrophoresis process.The interlocking microporous cells of this material reduce electricalresistance to the flow of current and the material does not absorbprotein. It will be seen that it is very simple to detach the specimensonce the electrophoresis process is com pleted. This is simply a matterof removing the small elements 70 and then removing the strips forfurther analysis.

It will be appreciated that the electrophoresis chamber itself is, aspreviously indicated, preferably formed of a plastic material which ismolded into shape and which has a dielectric characteristic, thethickness of the Walls being such that the magnetic forces between thestrips 60 and the elements 70 can be effective to the purpose stated.

We claim:

1. In an electrophoresis chamber having spaced support ridges forbridging specimen strips, a plurality of magnetic elements positioned onopposite sides of a wall of a supporting ridge, one of said elementsbeing removable to selectively engage a specimen strip and hold itagainst a supporting wall by the force of the electromagnetic attractionof said elements.

2. In an electrophoresis chamber having spaced support ridges forbridging specimen strips, a plurality of holding elements formed ofmagnetic material, said elements being selectively positioned on theoutside of said support ridges each to engage a portion of the end ofthe specimen strip to hold the strip in bridging relation between saidridges, and means to create a magnetic field to attract said elementstoward said support ridges to create a frictional engagement with thesurface of said ridges wherein said elements are magnetically supported.

3. An electrophoresis chamber comprising a relatively shallow tray offormed dielectric material having hollow supporting ridges formed in thebottom thereof in separate chambers within the said tray, said ridgesextending upwardly from the bottom of said tray to serve as a supportfor bridging specimen strips, and a strip of magnetic materialpositioned on the inner surface of the outside wall of said supportingridges, said strip of magnetic material being adapted to cooperatemagnetically with a plurality of short magnetic elements positionedselectively on the outside surface of the outside wall of said ridges tocreate a frictional engagement with the end of a specimen stripinterposed between said elements and said outer surface.

4. A device as defined in claim 3 in which the strip of magneticmaterial is a permanent magnet having a north pole along one edge and asouth pole along the other edge, and said elements have a north andsouth pole spaced similarly to that of the strip wherein the elementsare attracted to the wall of the ridge to a fixed position.

5. A device as defined in claim 3 in which the strip of magneticmaterial has linear-1y extending north and south pole regions spacedlaterally of the strip for cooperation with said magnetic elements whichhave a north and south pole region spaced substantially similar to thoseof the strip wherein the elements are attracted to the Wall of the ridgeto a fixed position.

6. A device as defined in claim 5 in which the elements are providedwith indicia to indicate a position of application in which mutuallyattracted pole areas of the strip and the elements will register.

7. In an electrophoresis chamber having spaced supports for specimenstrips arranged in bridging relation over said supports, a means ofsecuring the ends of said strips comprising a strip of magnetic materialdisposed longitudinally along said supports, and a plurality of shortpieces of magnetic material removably positioned over the ends of thespecimen strips and acting to hold said strips on said spaced supportsby the force of magnetic attractions between said strip of magneticmaterial and said pieces.

References Cited UNITED STATES PATENTS 2,557,399 6/1951 Teetor 335-2852,693,370 11/1954 Wheatley 335-285 6 McDonald et a1. 204-180 Pickels etal 204-299 Atkinson 248-206 Daline 248-206 Schumacher 204-180 J OHN H.MACK, Primary Examiner.

E. ZAGARELLA, Assistant Examiner.

1. IN AN ELECTROPHORESIS CHAMBER HAVING SPACED SUPPORT RDGES FORBRIDGING SPECIMEN STRIPS, A PLURALITY OF MAGNETIC ELEMENTS POSITIONED ONOPPOSITE SIDES OF A WALL OF A SUPPORTING RIDGE, ONE OF SAID ELEMENTSBEING REMOVABLE TO SELECTIVELY ENGAGE A SPECIMENT STRIP AND HOLD